Does the NAV system in the 2007+ models, or any model I guess, run similar to I-Drive without the knob?

I guess what I want to know is if you get the NAV, do you get upgraded interior features like with IDrive, or is it simply a NAV screen.

Does the PDC show up on the screen or is it on audible? Can I change the seat heating locations? HVAC control? Parked car HVAC control?

Is there a users manual that I can be linked too? I am looking at purchasing a 2007+ model, but if the NAV system is only used for NAV, then I dont really need it, but if it operates similar to IDrive, then I think that it might be worth the $2900 premium it commands.